1. Field of the Invention
The present invention relates to image forming apparatus such as color printers, color copying machines, and color facsimile machines. More particularly, the present invention relates to a printing apparatus of the tandem type in which a plurality of image-forming sections are aligned along the transport path of a print medium to sequentially form toner images of respective colors in registration with one another on the print medium.
The present invention also relates to a printer of an intermediate transfer method in which images are formed by a plurality of image forming sections and transferred onto an intermediate transfer material and then the images are further transferred from the intermediate transfer material to a print medium.
2. Description of the Related Art
Known image forming methods for color printers, color copying machines, and color facsimile machines are, for example, an intermediate transfer belt method and an intermediate transfer drum method including tandem type.
With a tandem type printer, yellow, magenta, cyan, and black images are formed by corresponding image forming sections and transferred onto a print medium in superposition. The prominent feature of a tandem type printer is that an image of four colors can be printed by a single passage of a print medium through the transport path.
A conventional printer is so designed that unless all of the image-forming sections are attached to the printer body properly, printing is not performed for any colors in combination, even a single color. If any one of the image-forming sections is not attached properly, an error handling operation is performed. Thus, even when a user wishes to print only black and red images, cyan and yellow image forming sections must be attached to the printer body. This is uneconomical.